Japanese encephalitis - Vaccination

Vaccination

The vaccines are produced in the brains of mice and contain viruses from them. Additionally the vaccine contains thimerosal, formaldehyde, dextran and gelatin. The vaccines are not approved in Germany and must be ordered via an international pharmacy when they are required. The vaccination can be administered at tropical institutes and large vaccination centers. It is only recommended for people who spend more than four weeks in a risk area.

In the mean time there is a vaccine which has been approved in Germany: IXIARO, whose viruses and virus components are bred on verocells. These are then adsorbed on aluminum hydroxide for a stronger vaccine reaction. It is recommended that IXIARO not be used for children and adolescents due to the fact that there is no data as yet on safety and efficacy.

Immunity

After the third vaccination there supposedly is an immunity of approx. 80-90%. The protection provided by the vaccination lasts several years. A sero conversion rate of 29.4% 10 days after the first vaccination was observed for IXIARO. One week after the second vaccination it was 97.3%.

Adverse effects, vaccine complications and vaccine damages of the Japanese Encephalitis Vaccination

The vaccines are difficult for people to tolerate. In 50% of people who have been vaccinated there are problems at the site of injection and there are general symptoms such as headaches and joint pain, nausea and fever.

Frequently allergic reactions occur, mainly in people who have an allergic disposition. The range of reactions includes urticaria and anaphylactic shock.

Severe neurological damages are rare, but in Japan they occur in one out of 500000 people who have been vaccinated.(Takahashi H., Pool,Tsai,Chen,:Adverse events afterJapanese encephalitis vaccination: review of post marketingsurveillance data from Japan and the United States. The VAERS Working Group, Vaccine 2000, 18(26):2963-2969)

In South Korea the high number of lasting vaccine damages has led to the establishment of a fund for damage claims. (Martin Hirte: Impfen:pro&contra, 2001, S. 312)

Adverse effects occur in about 40% of the people who have been vaccinated with the new vaccine IXIARO. They generally occur within the first three days after the vaccine has been administered.

Diseases of the blood and the lymph system Rare: LymphadenitisDiseases of the nervous system Very frequent: Headaches Occasional: migrane, dizzinessDiseases of the ear and the labyrinth Occasional: VertigoDiseases of the respiratory system, the chest and mediastinum Occasional: Pharyngolaryngeal painDiseases of the gastrointestinal tractFrequent: Nausea Occasional: Diarrhea, vomitingDiseases of the skin and subcutaneous tissue Frequent: Rash Rare: ItchinessDiseases of the skeletal muscle, conjunctive tissue and bones Very frequent: Muscle painGeneral afflictions at the site of injection Very frequent: Reactions at the site of injection (pain/pressure pain) Frequent: Fatigue, flu-like symptoms, fever, reactions at the site of injection (redness, hardening, swelling, itchiness) Occasional: chills, reactions at the site of injection (bleeding, bruises)Tests Occasional: Elevated liver enzyme values

The evaluation of adverse effects frequently is based on the following definitions of frequency: Very frequent: =1/10 Frequent: =1/100, <1/10 Occasional: =1/1.000, <1/100 Rare: =1/10.000, <1/1.000 Very rare: <1/10.000, not known (frequency cannot be estimated on the basis of the available data)

The duration of the period of time during which the adverse effects were observed unfortunately is not known.